using System;
using System.IO;

namespace ln.logging
{
    public class FileLogger : LoggingBackend, IDisposable
    {
        FileStream fileStream;
        TextWriter writer;

        public FileLogger(string filename)
        {
            openLogFile(filename);
        }

        private void openLogFile(string filename)
        {
            if (File.Exists(filename))
            {
                String oldfn = String.Format("{0}.old", filename);
                if (File.Exists(oldfn))
                    File.Delete(oldfn);
                File.Move(filename, oldfn);
            }
            fileStream = new FileStream(filename, FileMode.Create);
            writer = new StreamWriter(fileStream);
        }

        public void Close()
        {
            if (writer != null)
            {
                writer.Close();
                fileStream.Close();
            }
        }

        public void Dispose()
        {
            if (writer != null)
            {
                writer.Close();
                writer.Dispose();
                writer = null;
            }
            if (fileStream != null)
            {
                fileStream.Close();
                fileStream.Dispose();
                fileStream = null;
            }
        }

        protected override void MessageReceived(LogLevel logLevel, string[] lines)
        {
            if (writer == null)
            {
                throw new ObjectDisposedException("FileLogger has already been disposed");
            }

            lock (writer)
            {
                foreach (String line in lines)
                {
                    writer.WriteLine(line);
                    writer.Flush();
                }
            }
        }


    }
}